Automatic door opening and closing device.



No. 798,976. PATENTED SEPT. 5, 1905. H. H. PRAHL & B. H. KISTNER. AUTOMATIC DOOR OPENING AND CLOSING DEVICE.

APPLICATION FILED APB,5,1905.

Jvitnmou umaaw. s cmnuu no mwunmmwin. wmmfcx u c UNITED STATES PATENT OFFICE.

HANS H. PRAHL AND EBER H. KISTNER, OF INDEPENDENCE, KANSAS.

AUTOMATIC DOOR OPENING AND CLOSING DEVICE.

Specification of Letters Patent.

Patented Sept. 5, 1905.

Application filed April 5,1905. Serial No. 253,951.

To (all whom, it 777/(LZ/ concern:

Be it known that we, HANS H. PRAHL and EBER H. KISTNERfillZiZQDS of theUnited States, residing at Independence, in the county of Montgomery and State of Kansas, have invented new and useful Improvements in Automatic Door Opening and Closing Devices, of which the following is a specification.

This invention relates to adevice for opening and closing boiler and other furnace doors, the object of the invention being to provide means actuated by a foot-lever which upon being depressed will automatically throw the door open, leaving the hands of the fireman free for raking the fire or feeding fuel thereto, together with associated means for automatically closing the door when the lever is released, thus obviating the necessity of keeping the door open during the entire operation of firing, whereby cooling of the furnace during the firing operation is prevented.

The preferred embodiment of the invention is illustrated in the accompanying drawings, in which Figure 1 is a fragmentary front elevation, the platform appearing in section, of a furnace and our improved door-operating means. Fig. 2 is a horizontal cross-section, on an enlarged scale,through the worm-shaftand yoke end of the operating-lever; and Fig. 3 is a vertical sectional view through the upper bearing-bracket and bearings on the line 3 3 of Fig. 1.

Referring now more particularly to the drawings, the numeral 1 represents a portion of the wall of a boiler or other furnace, and 2 the door thereof. Arranged vertically at one side of the door is a shaft 3, which projects downward through afioor or platform 4 and is journaled at its lower end in a suitablymounted bearing-bracket 5. Above the floor or platform 4 the shaft is squared or made polygonal in cross-section, the polygonal portion or section 6 receiving the knuckles 7 of hinge-straps 8, fastened to the door, whereby the latter is mounted to swing with the shaft to open and closed position. The upper knuckle 7,01- both knuckles, if desired, may be provided with a set-screw 9 to fix it to the shaft-section 6, and said knuckles rest upon and are supported by bearings 10 and 11, mounted upon a bracket 12, secured to the front wall of the boiler 1.

The bracket 12 is made of a single piece of strap metal and comprises a vertical body portion 13, formed at its upper and lower end with forwardly-projecting arms 14 and 15, each of said arms having an opening 16 for the reception of the shaft-bearings. The bearings 10 and 11 are externally circular in form to fit and turn within the circular openings 16 and have squared or rectangular bores for the reception and passage of the shaft-section 6. Each bearing is provided at its upper end with a flange 18 to rest upon its respective bracketarm, and the upper bearing 10 is provided with a set-screw to lock it to the arm. The knuckles 7 rest upon the upper flanged ends of the bearings, and the upper knuckle is formed at its base with a flange 20, corresponding in area with the flange of the bearing 10, so as to rest firmly and securely thereon.

Below the floor or platform 4 the shaft 3 is enlarged and may be circular in form to provide a shaft-section 21, which is formed with spiral grooves 22, thus producing, in effect, a worm-shaft. Mounted for longitudinal movement on this shaft 21 is a sleeve 23, carrying stud-shafts 24, on which are mounted frictionrollers 25, arranged to travel in the grooves 22, the spiral formation of the grooves being such that when the sleeve is forced upward on the shaft the latter will be turned in one direction to swing the door open and when the sleeve is forced downward the shaft will be turned in the reverse direction to close the door. A coiled spring 26 surrounds the shaft 21 between the platform 1 and sleeve and serves to return said sleeve to its normal position at the lower end of said shaft.

Pivotally supported by a bracket 27 below the platform is an operating-lever 28, which is arranged at an outward and upward inclination and is provided at its lower end with a yoke 29, whose arms 30 are formed with short longitudinal slots 31 to receive studs or pins 32, pivotally connecting them with the sleeve 23, said slots permitting the studs to have sufficient movement therein to compensate for the slight rotary play of the sleeve and pivotal movement of the lever when the shaft is actuated. The upper end of the lever 28 carries a pivoted rod 33, which projects vertically upward through an opening in the platform 4 and is provided with a foot-plate 34, roughened or serrated to prevent slipping of the foot thereon.

lVhen it is desired to open the door, the fireman places his foot upon and depresses the plate or pedal 34, thereby swinging the yoke 10 of the lever upward and causing the sleeve 23 to slide upward on the shaft 21, the rollers 22 in this operation causing the shaft to be tation of the shaft, whereby the door is swung closed. It will thus be seen that the fireman may open the door in such manner as to leave his hands free for raking or firing and that as soon as his foot is removed from the pedal the door will be automatically closed, thus preventing the furnace from cooling to any material extent during the firing operation; also, that the invention provides a simple, convenient, and effective construction of means for automatically opening and closing the door in the described manner.

From the foregoing description, taken in connection with the accompanying drawings, the construction and mode of operation of the invention will be understood without a further extended description.

Changes in the form, proportions, and minor details of construction may be made within the scope of the invention Without departing from the spirit or sacrificing any of the invention.

Having thus described the invention, what is claimed as new is 1. In an automatic door opener and closer, the combination of a shaft having an upper polygonal portion and a lower cylindrical portion provided with worm-grooves, a pivotal support for the lower end of the shaft, a supporting-bracket, bearings j ournaled upon said bracket and mounted upon the upper polygonal portion of the shaft, a door, supports for the door having eyes or knuckles mounted upon the polygonal portion of the shaft and supported by said bearings, a sleeve arranged to reciprocate upon the cylindrical portion of the shaft and provided with friction-rollers coacting with said grooves, a foot-lever for moving the sleeve in one direction, and a spring surrounding the shaft and bearing on the sleeve for restoring said sleeve to its normal position.

2. In a door opening and closing device, the combination of a bracket provided with arms having openings, bearings journaled in said openings, a shaft suitably journaled at its lower end and projecting at its upper end through said bearings,the said upper end of the shaft being squared and the bearings having corresponding openings for the passage of the same, a door, straps connected with the door and provided witheyes having square sockets and mounted upon the squared portion of the shaft and supported by the bearings, a footlever, means operated by said lever and engaging the lower end of the shaft for oscillatfing movement, said means serving when the lever 1s depressed to swing the same 1n onedirection, and further means for restoring the aforesaid means to normal position and turning the shaft in the reverse direction.

3. In an automatic door opening and closing device, the combination of a shaft having a worm portion and adoor-supporting portion, a door mounted upon said door-supporting portion, said worm portion being provided with spiral grooves, a sleeve arranged to traverse the worm portion and carrying frictionrollers traveling in said grooves, a spring surrounding the shaft and compressed by the sleeve on its upward movement and serving to return the same tonormal position, and a foot-lever for moving the sleeve upward on the shaft, substantially as described.

I. In combination with a furnace, and a supporting floor or platform arranged at the front thereof, a shaft extending upwardly through said floor or platform and provided below the same with a worm portion, a furnace-door connected with the shaft above the floor or platform, a sleeve operatively connected with the worm portion of the shaft, a lever fulcrumed to the floor and connected with said sleeve, the sleeve adapted when moved upwardly on the shaft by the lever to rotate said shaft and swing the door open, a spring surrounding the shaft between the sleeve and floor and compressed by the upward movement of the sleeve and adapted to expand and return the sleeve to its normal position, thereby actuating the shaft to swing the door closed, and an operating member attached to the lever and projecting upwardly through the floor or platform adjacent to the door.

In testimony whereof we aflix our signatures in presence of two witnesses.

HANS H. PRAHL. EBER H. KISTNER.

Witnesses:

JOHN BERTENSHAW, GEO. HILL. 

